The opponent of offshore drilling argues that the benefits of drilling new oil wells in certain areas do not outweigh the risk of environmental disaster from drilling those wells. As evidence, she points to the fact that the wells already in those areas only provide 4 percent of the country's daily oil needs, and the new wells would add less than one percent.

The drilling proponent counters this argument with an analogy meant to show that the opponent's reasoning doesn't make sense. By the opponent's logic, it would be possible to conclude that new farms should not be allowed, since any given new farm could supply no more than a tiny fraction of the country's total food needs. By using an analogous argument where the conclusion is clearly unreasonable, the drilling proponent undermines the opponent's reasoning.

The drilling proponent counters the drilling opponent's position. He does this by using an analogous argument where the opponent's logic leads to an unsupported conclusion.

It's worth noting that the major flaw in the opponent's argument is that she provides insufficient evidence for her conclusion about benefits versus risk. Without more information, there's no way of knowing whether 4 percent or half of one percent is a significant number or not, and without knowing how big the risk of environmental disaster is, it seems like a jump to conclude that those benefits are smaller than the risk. Though the drilling proponent does not directly call out this flaw, the point of his analogy is to show that the conclusion about banning new farms is clearly unsupported by evidence pointing only to the small benefits of each new farm — in the same way that the drilling opponent's conclusion about oil wells is unsupported, because it relies only on evidence about the (apparently) small benefits provided by the new wells.